Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

Hello Mr. Tore,


This photo is of the bulkhead inside the forward torpedo room...  Do you remember what would be located at the red circled location?


Regards,
Don_

[tore]

Don.
Sorry I cannot remember, to me it looks like a bracket for a gyro repeater, a lot of stuff were mounted on this bulkhead particularly electronics related to Nato surveillance after my time. The small hooks up on the top of the image were hooks for the brigde rain coats to be dried.

Tore.

[tore]

Don.
Returning to your question of today I am posting an U-Historia image of the equipment hooked up to the item you questioned. As you see it is indeed more to it than just a bracket and as I assumed related to surveillance installed after my time. I guess everything of this installation is classified and removed.

Tore

[Raymic1]

1.Mr. Tore..was there supposed to be a U-Historia picture attached?


2. Ref the original inquiry, there is at least 3 of these White Circle mounts on U995.
Attached is a picture from the Rear torpedo room one, above the Electric Compressor.
There is also an electric wire that runs into the back of each of these  'White Circles'

[tore]

Raymic1
Sorry somehow my U-Historia image was not posted hope my second try works.


Tore

[Don Prince]

Hello Mr. Tore,


I have a question about roll stability with the Type VII C U-Boat:


1. When FBT 2 and FBT 4 are in the fuel oil configuration, the U-Boat sets lower in the sea water and this would add to the roll stability because the center of gravity is lower compared to the water surface. Therefore, the U-Boat has a degree of roll stability.


2. However, when FBT 2 and FBT 4 are in the water ballast configuration, the U-Boat sets a little higher and the water line is raised. But, FBT 2 and FBT 4 empty tanks also provide stability against rolling.


Is one state better than the other for roll stability, or are they about the same?


Regards,
Don_

[tore]

Don.
 Sorry about my late answer, I have just returned from my summerfarm where the access to the net is limited.
The transvers stability of a submarine is a bit complex and consist more elements than saddle tanks and fuel, in general you might say it has many variables as follows:
 1. Stability on the surface where the submarine acts like any surfaceship and the stability is governed by the metacentric hight.
 2. Stability submerged where the submarines transverse stability is created by the distance of the submarines center of gravity and center of boyancy. A proper way of obtaining transverse stability is placing heavy equipment between the submarines center of gravity and center of boyancy. A proper stability is achived by by putting heavy equipment like batteries as low as possible.
 3.The complicated stability while breaking the surface when the metacentric hight reduces, hence the tranverse stability as you ascend and break the surface. The COs normally like to have a check on the wind and waves to put the submarine in the right position as you break the surface  when the tranverse stability is low. I have experienced excessiv heeling of more than 45 degrees during surfacing. As far as I remember the batteries could take 60 degrees before spilling acid.

     Tore

[Don Prince]

Hello Mr. Tore,


Which state would you consider more roll resistant with a U-Boat Type VII C on the surface:
1. U-Boat in fuel oil reserve mode with the saddle tanks full, the U-Boat is about 9 inched lower in the sea as is the center of gravity.
Or
2. U-Boat saddle tanks in the water ballast configuration, and the air filled saddle tanks on the side of the pressure hull resisting the roll motion.


Regards,
Don_

[tore]

Don.
As mentioned before a submarines transveres stability has many variables and saddletanks introduces many more, without going into the metacenctric hights and naval architects math. you may say filling the seawater compensated saddletanks with fuel introduces a rise of the submarines center of gravity and weight, this shall normally reduce the transverse stability. With the saddle tanks filled with air and no water creating surface effect the submarine looses weight and the center of gravity sinks, hence the stability increases.
Tore

[Don Prince]

Hello Raymic1,


Paul "TheEngineeringGuy" on the CrushDepth Website discovered that the plates were for a mechanical clock. I tend to believe this is true because to the three (3) mounting holes. Also, The clocks were the first thing to be pilfered from the U-Boats after WWII...


Regards,
Don_

[Raymic1]

Thanks, Don for the clocks. Very interesting.


I also took this still from a video on FB off a Fort Aniota Museum at Fort Zachodni Poland.
It looks like a Mergus-type Uboat Toilet but is not as complex.?

[Raymic1]

Also in regards to the clocks. Here is a close-up view of the back of the circular plate in the rear Torpedo room.
You can see some sort of electrical wire or pneumatic cable going into the back of it. So possible the clocks were powered either this way?

[Don Prince]

Hello Mike,


I believe that view of the back of the mounting plate is a bit misleading. This front view of that plate does not show any hole towards the center. Besides ,the U-Boat clocks were key wound as you can see on the clock face just above the 6 in the photo that I previously posted...


Regards,
Don_

[Raymic1]

Yes your right. A bit of parallax in the rear pic....

[tore]

Being immobilized for a few weeks due to the gout made me some sparetime to re-arrange my e-painting of KNM Kaura, ex U 995. It is pretty much the same image as previously published. A fiction of KNM Kaura in the Vestfjord, Northern Norway, above the artic circle, where we usually were patrolling, escorted by a group of killer whales while passing the lighthouse Kaura (where KNM Kaura got its name from) and the old steamer S/S Finmarken (the lifeline to the rest of the world). The image is a fiction from 1953, part of it published in 2017. Might be some of the present days follower haven`t seen it.
Tore